US Magazines: Billboard

The 08 May issue of US magazine Billboard features Madonna in the front cover collage celebrating Glee. In the article inside mentions how Glee creator Ryan Murphy got Madonna onboard:

The Madonna episode was the first time the music on the show was turned over in its entirety to one performer - and in the beginning getting the artist onboard was a challenge.
'Her camp did say 'no' originally, but we had gone in cold with little explanation as to what 'Glee' and Ryan Murphy's master episode plan was,' the show's music supervisor PJ Bloom says. 'Ryan closed the deal with an amazing appeal in letter form to Madonna, not just as the creator and driving force behind the show but as a lifelong fan.'